Sector: Large 4×4 Price: £48,730 Fuel: 33.2mpg CO2: 223g/km

The second-generation R350 CDI is a car with a very small audience – it’s for those who really must have a four-wheel drive car, but the thought of sitting high up makes them feel giddy.

At least, that is the case in the UK – across the Atlantic this car is in its element on the wide open freeways of the US. But in small, cramped Blightly it doesn’t have the same kerb appeal.

Which is not to say it isn’t a good car. Call it an overgrown MPV, a diminutive SUV or, as I prefer, an S-Class estate, and you get some idea of this car’s size. As with the Audi Q7, it’s one of the few cars that you drive in the UK and become very aware of its dimensions. Country roads have you breathing in as an on-coming car passes by, while twisty lanes show up the lack of dynamicism in the chassis (not helped when the kerb weight is nearly 2.3 tonnes).

But get on to a smooth, straight road and you can cover serious distances in utter comfort and, thanks to a new generation diesel engine, enjoy fairly tolerable fuel economy. The 3.0-litre V6 diesel under the bonnet of the R350 CDI emits 223g/km of CO2 and returns a claimed 33.2mpg on the combined cycle – not the sort of figures that will win a green fleet award, but not too bad when you consider the 265bhp and mighty 457lb-ft of torque available from 1,600rpm.

Simply push the throttle into the deep carpet and the big V6 rumbles into life, surging you forward with more pace than a car of this size and weight should have. A smooth seven-speed automatic gearbox goes about its business unobtrusively, eventually slotting into top gear and delivering seriously impressive low revs at motorway speeds.

That’s this car’s key attribute – it can carry seven people (the rearmost two seats are just about useable by adults) and some luggage, even with the third row of seats in place.

For most people, an M-Class or E-Class estate will do the job just as well, leaving the R-Class as a very big car filling a very small niche.

Verdict:

A car in a segment all of its own, the R-Class is an unusual but capable option for those needing MPV practicality with the added traction of four-wheel drive. That it's also relatively efficient and hugely luxurious are great bonuses.